1. Field of the Invention
The present invention relates to a power-driven rolling and receiving apparatus. In particular, this invention relates to an improved structure of the power-driven rolling and receiving apparatus.
2. Description of the Related Art
The driving method of the rolling and receiving apparatus, such as the roller blind, the Rome blind, the horizontal-typed blind, the projection screen, and iron roller gate, has been changed to a power-driving method from a manual-driving method. The power-driven rolling and receiving apparatus uses the induction motor or the DC brush motor as the power source.
Because the induction motor needs a lot of silicon steel flakes and inductance coils, the dimension of the power-driven rolling and receiving apparatus using the induction motor as the power source is large and its weight is heavy. Furthermore, the rotor copper loss is high when the induction motor is operated so that the cooling efficiency is low and the temperature is high. When the induction motor is operated at a low speed, the torque is inadequate.
For the power-driven rolling and receiving apparatus using the DC brush motor as the power source, when the rotor of the DC brush motor rotates to the switch point, the switch flake and the carbon brush of the DC brush motor performs a current switch operation to make the rotor rotate continuously. However, in performing the current switch operation, the carbon brush is worn by the switch flake. When the DC brush motor operates for a long time, the carbon brush becomes aging so that the characteristic of the DC brush motor becomes worse. Therefore, the carbon brush must be replaced at a regular time schedule. The maintain cost increases. Furthermore, when the current switch is performing, a spark is generated so that the DC brush motor is not suitable for operating at a high speed, for a long time, or a dangerous location.